core Estimated learning time: 5 h

10.1 Architecture principles that hold up

You can review a design against named principles instead of taste.

Design review needs named principles or it collapses into taste, and this topic supplies them: the Well-Architected pillars, twelve-factor applications, stateless design, and the operational trinity of idempotency, retries with backoff, and timeouts everywhere. It opens the architecture module because the patterns that follow are these principles composed. The phrase doing the most work is designing for the failure you expect this year — not the exotic one, the ordinary one: a zone down, a dependency slow, a deploy bad.

Work through these

The Well-Architected pillars and how to run a review
Each provider publishes a set of pillars for reviewing a design, and the value is having named criteria instead of opinions. Running a review against them is a repeatable exercise rather than a discussion.
AWS Well-Architected Framework · Reference
Twelve-factor applications and stateless design
The twelve-factor guidelines describe applications that can be started, stopped and duplicated freely, and statelessness is the property that makes all of it work. This is the shape cloud platforms expect.
The Twelve-Factor App · Reference
Idempotency, retries with backoff, and timeouts everywhere
An operation safe to repeat, a retry that backs off instead of hammering, and a timeout on every call are three habits that prevent a small failure becoming an outage. Their absence is how retry storms happen.
Designing for the failure you expect this year
Designing for the failure you actually expect this year is more useful than designing for every conceivable disaster. Naming that expected failure is what makes the design decisions concrete.

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Links last checked 29 Aug 2026.

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